PRIMARY KEY ( column_name [, ... ] ) index_parameters | EXCLUDE [ USING index_method ] ( exclude_element WITH operator [, ... ] ) index_parameters [WHERE( predicate ) ] | FOREIGN KEY ( column_name [, ... ] ) REFERENCES reftable [ ( refcolumn [, ... ] ) ] [ MATCH FULL ...
[ { UNION | INTERSECT | EXCEPT } [ ALL | DISTINCT ] select ] [ ORDER BY expression [ ASC | DESC | USING operator ] [ NULLS { FIRST | LAST } ] [, ...] ] [ LIMIT { count | ALL } ] [ OFFSET start [ ROW | ROWS ] ] [ FETCH { FIRST | NEXT } [ count ] { ROW | RO...
Summary: in this tutorial, you will learn about the PostgreSQL foreign key and how to add foreign keys to tables using foreign key constraints. Introduction to PostgreSQL Foreign Key Constraint In PostgreSQL, a foreign key is a column or a group of columns in a table that uniquely identifies ...
SET CONSTRAINTS设置当前事务的约束检查模式。SET CONSTRAINTS { ALL | name [, ...] } { DEFERRED | IMMEDIATE }SET SESSION AUTHORIZATION为当前会话设置会话用户标识符和当前用户标识符。SET [ SESSION | LOCAL ] SESSION AUTHORIZATION username SET [ SESSION | LOCAL ] SESSION AUTHORIZATION DEFAULT RESET ...
Unique Constraints: ensure that the data contained in a column, or a group of columns, is unique among all the rows in the table. Primary Keys Constraint: both unique and not null. A table can only hasONEprimary key, although this primary key can be a group of columns (a composition ...
您可以使用 Azure 資料庫移轉服務,從內部部署 PostgreSQL 安裝線上移轉到適用於 PostgreSQL 的 Azure 資料庫。在線上移轉案例中,Azure 資料庫移轉服務會將所有現有資料複製到 Azure,再從來源資料庫持續執行同步作業。 任何對內部部署系統執行的新交易,都會複製到 Azure 中的新資料庫。 此程序將...
Foreign-key constraints: "t_f_f1_fkey"FOREIGN KEY(f1)REFERENCES t_p(f1) Distribute By: SHARD(f1) Location Nodes: ALL DATANODES 外键使用限制 外键只是同一个节点内约束有效果,所以外键字段和对应主键字段必需都是表的分布键,否则由于数据分布于不同的节点内会导致更新失败。
ccu.column_nameASforeign_column_nameFROMinformation_schema.table_constraintsAStcJOINinformation_schema.key_column_usageASkcuONtc.constraint_name = kcu.constraint_nameANDtc.table_schema = kcu.table_schemaJOINinformation_schema.constraint_column_usageASccuONccu.constraint_name = tc.constr...
[ LIMIT { count | ALL } ] [ OFFSET start [ ROW | ROWS ] ] [ FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } ONLY ] [ FOR { UPDATE | NO KEY UPDATE | SHARE | KEY SHARE } [ OF table_name [, ...] ] [ NOWAIT | SKIP LOCKED ] [...] ] ...
group中需要添加DN节点,每个group会均匀分配总共4096个shardkey。 下面演示如何创建一个default group: 1.切换为tbase用户 su tbase。 2.连接数据库:注意:是连接到cn节点(后面没特别说明,所有数据库操作都是连接到cn节点)。 3.查询当前什么数据节点(DN),这些DN节点就是上面初始化集群时建立的。 postgres=# select...